Contour replicating devices for preparation of pipes to be joined by a saddle joint are well known in the art. Many of the early designs intended for this purpose incorporated a plurality of rods mounted to a member that encircles a pipe. For example Wurts' U.S. Pat. No. 776,713 discloses a flexible band adapted to be opened and included series of adjustable rods mounted thereon. Similarly, Turner's U.S. Pat. No. 2,222,127 discloses a retainer ring made of link elements pivotally interconnected wherein each link member includes a movable indicator.
Several other early designs include mechanisms that grip or are connected to the contour measuring device to hold the same in place. For example Bugenhagen's U.S. Pat. No. 2,380,919 discloses a conformator gauge supported from a hinged arm that extends from a supporting base. Moore's U.S. Pat. No. 2,466,464 discloses a guide head having stepped plates that are movable on a centrally disposed centering member that is held in place by an arm having a slidable clamp. Similarly, U.S. Pat. Nos. 2,533,500; 2,615,255; and 2,615,255 issued respectively to Parsons, Rankin and Rushing disclose contour gauges that in one way or another have a positive connection to one of the pipes being measured.
A few of the later designs were directed to contour gauges that could adjust in a way to accommodated pipes and structures of various sizes and diameters. For example Barnes U.S. Pat. No. 2,671,273 discloses a plurality of pins that project through a readily deformable band. Madden's U.S. Pat. No. 3,419,965 discloses a profile transferring device having a plurality of gauge units that connect together to form a long chain to follow long contours. Pruett's U.S. Pat. No. 3,550,278 discloses a pipe intersection marker having a a plurality of wedge shaped ribs attached to a belt that is adjustable in length.
Other recent designs include Halstead's U.S. Pat. No. 3,983,632 which discloses a contour transfer device including a pair of bars shaped and clamped together having a row of finger receiving openings through which transfer fingers are slideably mounted. Farris' U.S. Pat. No. 4,419,828 discloses a tubular pantograph mechanism that is adjustable in diameter, and has circumferentially spaced elongated rods mounted on the inner wall in parallel relation with the axis. Ming-Chin's U.S. Pat. No. 4,807,369 patent discloses a development drafter having a flexible strip that includes a plurality of integrally formed parallel tubular pin holders disposed to receive a plurality of pins wherein the flexible strip is adaptable to wrap around a pipe. Similarly, U.S. Pat. No. 5,383,282 by Field et al discloses a plurality of pins held in a flexible band that is capable of circumferentially enclosing a tube. As can be seen, many variations of contour gauge designs have been introduced over the years.
While most the above noted contour reproducing devices adequately perform the task of duplicating the line of an irregular surface, each are to some extent either complicated in design, difficult to use, expensive to manufacture, or produce imprecise results. Accordingly, a need remains for a contour gauge that produces accurate results yet is simple in construction, easy to use, and inexpensive.